Can you shed some light on your statement that insulin resistance is good for fat loss? From my understanding, high amounts of blood sugar typically lead to weight and ultimately fat gain. Always enjoy your posts.
I'll do what I can in a post, but please recognize that to learn and appreciate fully insulin resistance as a concept could take up most a full course of study in its own right, so this is going to be my best attempt.
First, do not confuse the enhancement of insulin resistance on fat loss with any judgment of insulin resistance being a state that I
advocate for, or think is healthy in sedentary individuals; this is obviously unhealthy, associated with the metabolic syndrome, diabetes, not to mind central abdominal adiposity, etc.
Insulin resistance is a state wherein the body's tissues (e.g., liver, pancreas, skeletal muscle) no longer recognizes the body's insulin and continues to produce glucose in inappropriately high quantities (the effect rather than causative, though toxic levels of glucose do degrade the pancreatic islet cells' responsiveness to insulin as one pathway/mechanism of insulin resistance, feeding back to worsen insulin resistance).
As we know, fat loss occurs with the GLP-1 & GIP agonists that are insulin sensitizing. Still, it is not insulin sensitivity per se that is responsible for this effect - indeed high blood glucose in itself neither enhances fat gain nor inhibits fat loss - but rather, fat loss occurs due to the other effects of these drugs such as altered food preferences, delayed gastric emptying, satiation, that promote appetite control and reduce energy intake.
In fact, the vast majority of fat loss agents promote insulin resistance, e.g., β-agonists, stimulant drugs like caffeine and ephedrine, these all either act analogously to or increase the action of catecholamines (epinephrine, norepinephrine, or adrenaline and noradrelanine).
When tissues like the liver and fat cells fail to be stimulated by insulin, glucose is not taken up by the cells. Without glucose, the liver begins to metabolize free-fatty acids (increasing ketone levels in the blood), preventing them from being re-esterified into fat cells. In liver & fat cells, without insulin being taken up into these tissues, there is suppression of fat synthesis/lipogenesis (adipocyte) & VLDL synthesis (liver).
Let's not forget the brain; when systemic blood glucose is elevated, it'll constantly have its favored energy source and keep us alive. We like that.
This might all sound perfectly rosy, but we like how the GLP-1 & GIP agonists work because insulin resistance during caloric restriction in skeletal muscle (70ish% of our cells, more in bodybuilders) is sort of a scary image, glycogen stores are first catabolized; then intramuscular triglyceride, and eventually, if the body has to, it will use proteins for energy to perform work.